All complex products and all products made by a complex manufacturing process should or must before use be subjected to a test by the manufacturer and/or the user, for example a function test or a parameter test. This is important in particular for semiconductor components because on the one hand these are manufactured in large quantities and on the other they are often used in safety-relevant areas of application (for example, integrated circuits in motor vehicles for ABS, airbag, ignition modules). The testing of these products, for example, the specific properties to be verified, is generally integrated by the manufacturer in the manufacturing process and performed in at least one test mode at the beginning of the manufacturing process and/or during the manufacturing process and/or on completion of the manufacturing process in a testing sequence with successive test operations for a large number of products. Usually at least one test mode is performed at the beginning of or during the manufacturing process of the products and one test mode at the end of the manufacturing process (after completion) of the products. For example, in the manufacturing process of semiconductor elements, it is usual for a test mode to be carried out on the semiconductor elements on the semiconductor wafer as so-called "samples" and a test mode to be carried out on the finally assembled and mounted semiconductor components as so-called "final measurement".
Every test operation in a test mode covers the determination of a large number of parameters characteristic for the properties of the product to be tested (for example mechanical, electrical or optical parameters) which are determined in sequential (i.e. successive) measuring operations (sometimes more than 1000 measuring operations are required for each test operation), and where the individual measuring operations of a test operation are usually performed on a computer-controlled automatic testing machine. Because of the scatter in the manufacturing process (process steps with a high degree of scatter) and the frequently high quality requirements, the products to be tested should be subjected to a 100% test. This 100% test, however, necessitates that all measuring operations in a test operation be performed, and this involves high costs (especially when there are several test modes in a manufacturing process). In some cases, the cost of testing a product must be assumed to be one-half of the manufacturing cost.
In the literature reference Milor, L., Sangiovanni-Vintentelli, A. L., "Minimizing Production Test Time to Detect Faults in Analog Circuits", IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems, Vol. 13, No. 6, June 1994, pp. 796-813, a method is described for testing products where in a particular test mode, a variation of the sequence of the measuring operations is performed with respect to the duration of a test operation and the selection of a subset of measurement operations from the total of all measurement operations with respect to the quality requirements of the test mode. By means of an algorithm, a subset of measurement operations is determined on the basis of statistical information and the subset selected in such a way that a desired yield can be obtained. It is disadvantageous that the method can be used only when the individual measurement operations of a test operation can be interchanged at will in their sequence (that is, when there is absolutely no dependence between the individual measurement operations) and that the testing of the products within the successive testing sequence of a test mode always takes place with the same subset of measurement operations which results in the loss of statistical information for the measuring operations of a test operation for this test sequence and subsequent test sequences.